Police did not intervene in the rally, organized by the Solidarity group with City Hall's blessing. But when hundreds of protesters tried to march to the neighboring Lubyanka metro station after the rally, they faced police cordons. Protesters managed to break through one chain of riot police and Interior Troops but were eventually stopped and dispersed by officers, who pushed the crowd inside the metro.

Dozens were manhandled and detained.

Gazeta.ru reported that a soldier with the Interior Troops tried to reason with Navalny during the unsanctioned march. "Alexei, I understand everything, but you just can't," the soldier pleaded. Navalny was among those detained, Ekho Moskvy said.

Meanwhile, seeing voters' growing disenchantment with the ruling authorities, political survivor A Just Russia promised to boost its independence and the still-ruling United Russia hinted at liberalization — possibly under new leadership.

Outgoing President Dmitry Medvedev, the sole name on United Russia's federal ballot in Sunday's elections, may replace Prime Minister Vladimir Putin as party head, United Russia official Andrei Vorobyov said, Interfax reported.

The idea was previously voiced in September by Kremlin chief of staff Sergei Naryshkin, who said the swap might take place after the March presidential election, which Putin is poised to win.

Medvedev did not comment on the proposal during a news conference Monday, but instead said he might consider restoring the "none of the above" option at the ballots. The option was eliminated in 2006 after it started gaining popularity.

"There is nothing scary about it, but I think it's a pretty odd way of self-expression," Medvedev said about the "none of the above" option, Interfax reported.

He again said the government might bring back elements of single-mandate elections to help "bright leaders" whose careers have been stalled by the regional leaders who top party electoral lists.

At a separate news conference, Just Russia leader Sergei Mironov announced his own presidential bid, which is to be formalized at a party convention next week. A one-time ally of Putin, Mironov previously ran against Putin in the 2004 presidential election in what he said at the time was an attempt to support Putin's bid.

Mironov also said Monday that A Just Russia was ready for tactical alliances with both opposition parties and United Russia, but will be an independent player.

This may be a new task for the party created in 2006 with the Kremlin's blessing as a spoiler for the Communists. It fell out of favor with the authorities after it began siphoning votes off United Russia in regional elections.

A Just Russia nearly doubled its Duma representation from 38 to 64 seats after the Sunday elections, but apparently mostly through the protest vote. Recognizing this, party chairman Nikolai Levichev promised not to let down the expectations of the some 8 million people who cast their ballots for A Just Russia. "We know we got your votes as an advance, and we will do everything to keep your support," Levichev said.

Mironov, a former Federation Council speaker who was sacked by United Russia in April, also appeared to have embraced the idea of A Just Russia being independent.

"I understand that I have faced questions about how I could be critical of the authorities since I am one of them," he said. But the Duma vote "is an answer to those who said the party could only win through administrative resources."

Both Mironov and Levichev refused to give their views on the next Duma, saying the configuration of its numerous committees would be decided at talks with other parties.

"We hope that the distribution of positions will be more justified in the next parliament," Mironov said. United Russia controlled all the chairmanships in the outgoing Duma.

United Russia senior official Sergei Neverov said even the speaker's post was up in the air and urged the public to recommend nominees to the party.

But he also said the party remained happy with the current speaker, United Russia's Boris Gryzlov. It remained unclear Monday whether Gryzlov would keep the job.

The Communist Party, the runner-up in the Duma vote, said it would challenge the elections in court as fraught with violations, Interfax reported.

But its leader Gennady Zyuganov, who earlier promised to run for president in 2012, also said his party was willing to cooperate with A Just Russia and the Liberal Democrat Party.

The leader of the Liberal Democratic Party, Vladimir Zhirinovsky, announced his party was willing to nominate a prime minister from its ranks provided the government asked for a candidate.

He reiterated that he would run against Putin in the presidential race.

By contrast, the Right Cause party, which had the worst showing of all seven parties at the ballots, said it would not field a presidential candidate in March, Interfax reported.

No normalization of ties between Ukraine and Russia is likely unless the region of Crimea, now under Russian control, is returned to Kiev's sovereignty, Ukrainian Foreign Minister Pavlo Klimkin said Tuesday.

Boris Nemtsov, an outspoken critic of President Vladimir Putin and Russia's role in the Ukraine crisis, has been shot dead outside the Kremlin in a murder that underscored the risks taken by the Russian opposition.

The murder of Kremlin critic Boris Nemtsov has dampened any hope for a peaceful political transition in Russia away from President Vladimir Putin's government, Garry Kasparov, a prominent opposition voice, has said.

A spokesperson for Moscow's information technology department has denied media reports that some of the surveillance cameras around the Kremlin had been switched off at the time of Boris Nemtsov's murder.

The U.S. State Department and FBI have announced a $3 million reward for information leading to the arrest or conviction of Russian Yevgeny Bogachev, the highest bounty U.S. authorities have ever offered in a cyber case.